Cocaine and metabolites in human graying hair: pigmentary relationship

To assess differences in the binding of cocaine, cocaethylene, and benzoylecgonine among pigmented and senile white hairs of the graying human cocaine abuser.

A sheath of graying hair in the region around the apex of the head was gathered between the thumb and index finger then cut and removed about 2 mm proximal to the scalp. The graying hair was divided into pigmented and senile white of equal weights and lengths and then analyzed by gas chromatography/mass spectrometry chemical ionization. Twenty-nine such pairs were analyzed.

Male cocaine abusers, ages 33-55 years hospitalized for substance abuse. Informed consent was obtained and confidentiality assured.

Concentrations of cocaine, cocaethylene and benzoylecgonine in ng were assessed for each of 29 paired hair samples by gas chromatography/mass spectrometry chemical ionization.

There were statistically significant differences between pigmented and senile white sections of paired samples. Cocaine (ng/mg hair, mean +/- SD) was 31.5 +/- 30.2 for pigmented hair vs 14.9 +/- 19.8 for senile white portions; (p < 0.0001). Cocaethylene (ng/mg hair, mean +/- SD) 3.22 +/- 5.0 (pigmented) vs 0.52 +/- 0.88 (senile white); (p < 0.0016). Benzoylecgonine (ng/mg hair, mean +/- SD) 5.1 +/- 5.3 (pigmented) vs 3.9 +/- 4.8 (senile white); (p < 0.005).

Melaninated pigmented hair seems to bind more cocaine, cocaethylene and benzoylecgonine than white hair in the same subject.